The present invention relates to the field of communications, and, more particularly, to phased array antennas and related methods.
Antenna systems are widely used in both ground based applications (e.g., cellular antennas) and airborne applications (e.g., airplane or satellite antennas). For example, so-called xe2x80x9csmartxe2x80x9d antenna systems, such as adaptive or phased array antennas, combine the outputs of multiple antenna elements with signal processing capabilities to transmit and/or receive communications signals (e.g., microwave signals, RF signals, etc.). As a result, such antenna systems can vary the transmission or reception pattern (i.e., xe2x80x9cbeam shapingxe2x80x9d or xe2x80x9cspoilingxe2x80x9d) or direction (i.e., xe2x80x9cbeam steeringxe2x80x9d) of the communications signals in response to the signal environment to improve performance characteristics.
A typical phased array antenna may include, for example, one or more element controllers connected to a central controller. Among other functions, the element controllers process beam control signals generated by the central controller (e.g., beam steering signals and/or beam spoiling signals) and provide output control signals for each of the phased array antenna elements. More particularly, each antenna element may have a controllable device associated therewith (e.g., a phase shifter, attenuator, and/or delay generator), and the output control signals may be used to control a phase, attenuation, or delay thereof. Thus, the transmission or reception pattern may be varied, as noted above.
Phased array antenna designs can vary widely due to the numerous environments and applications in which they are used. As a result, the design of various components used in phased array antennas may also vary widely from one antenna to the next. This is particularly true of element controllers, which are typically designed to perform very specific element control functions based upon the intended use of the antenna. Thus, a common prior art approach is to implement element controllers in application specific integrated circuits (ASICs), which, as the name implies, are designed for one particular antenna application.
A drawback of this approach is that even slight changes in system requirements may dictate the use of different ASIC element controllers from one antenna to the next. Yet, the design and testing of an ASIC can be both expensive and time consuming.
Attempts have been made in the prior art to provide more xe2x80x9cuniversalxe2x80x9d communications equipment that is adaptable to changing system requirements. One example is disclosed in U.S. Pat. No. 5,999,990 to Sharrit et al. entitled xe2x80x9cCommunicator Having Reconfigurable Resources.xe2x80x9d The communicator is for use in a communications system, such as in a base station or hand held transceiver unit, and includes a plurality of reconfigurable resource units (RRUs) that can each be dynamically altered to perform different processing tasks. A controller determines the processing tasks to be supported by the communicator and configures the RRUs accordingly. More particularly, the communicator determines if one of the RRUs is already configured to perform a desired processing task. If not, the controller obtains the necessary configuration file for the desired task and determines an amount of resources required by the configuration file as well as RRU availability to determine which RRU(s) will perform the desired task.
While such a communicator may provide certain advantages when used in a base station, it may not be well suited for use as an individual element controller. One reason is that it may require a relatively large amount of processing capability as well as memory space to implement, which may not be practical in an element control ASIC because of cost and power constraints. This problem would become particularly acute in phased array antennas including numerous phased array antenna elements and a respective element control ASIC for each element.
In view of the foregoing background, it is therefore an object of the present invention to provide a phased array antenna including one or more element controllers that may be operated in multiple operating modes.
This and other objects, features, and advantages in accordance with the present invention are provided by a phased array antenna which may include a substrate and a plurality of controllable phased array antenna elements carried thereby, a central controller for providing a mode selection signal and beam control signals, and at least one multi-mode element controller connected to at least one of the controllable phased array antenna elements and the central controller. The at least one multi-mode element controller may be operable in a desired operating mode from among a plurality of operating modes based upon the mode selection signal from the central controller. Furthermore, the at least one multi-mode element controller may also generate output signals for the at least one controllable phased array antenna element based upon the beam control signals from the central controller. By having a plurality of operating modes, the multi-mode element controller may advantageously be used in numerous phased array antennas.
More particularly, the at least one multi-mode element controller may include a memory for storing temperature compensation data or other element calibration, and a processor cooperating with the memory for generating the output signals based upon the beam control signals and the temperature compensation data. The output signals may be digital output signals, for example, and the at least one multi-mode element controller may define a number of bits for the digital output signals based upon the mode selection signal. For example, automatic rounding can be set according to the variable number of output control bits.
The phased array antenna may also include a controllable device connected between the at least one multi-mode element controller and the at least one controllable phased array antenna element for controlling at least one of a phase, attenuation, and delay based upon the output signals. Further, the plurality of operating modes may include a phase control operating mode, an attenuation control operating mode, and a delay control operating mode. In addition, the beam control signals may be beam steering signals and/or beam spoiling signals, for example.
The at least one multi-mode element controller may also include an output register for storing and outputting the output signals, and a bus interface for receiving the mode selection signal and beam control signals from the central controller. Additionally, the at least one multi-mode element controller may be implemented in an application specific integrated circuit (ASIC), for example.
A multi-mode element controller for a controllable phased array antenna element is also provided according to the present invention and may include an interface for receiving a mode selection signal and beam control signals from a central controller and a processor coupled to the interface. The processor may be operable in a desired operating mode from among a plurality of operating modes based upon the mode selection signal, and the processor may generate output signals for the controllable phased array antenna element based upon the beam control signals.
A method aspect of the invention is for controlling a phased array antenna element using a multi-mode element controller. The method may include generating a mode selection signal and beam control signals, selecting a desired operating mode for the multi-mode element controller from among a plurality of operating modes based upon the mode selection signal, and generating output signals for the at least one controllable phased array antenna element using the multi-mode element controller based upon the beam control signals.